3 files changed, 24 insertions, 9 deletions

diff --git a/src/commands.c b/src/commands.c
index 7d30c88..56ff944 100644
--- a/src/commands.c
+++ b/src/commands.c
@@ -147,7 +147,7 @@ solve_parse_args(int c, char **v)
         a->opts->max_moves     = 20;
         a->opts->max_solutions = 1;
         a->opts->nthreads      = 1;
-        a->opts->optimal_only  = false;
+        a->opts->optimal       = -1;
         a->opts->can_niss      = false;
         a->opts->verbose       = false;
         a->opts->all           = false;
@@ -163,7 +163,7 @@ solve_parse_args(int c, char **v)
                         if (val < 0 || val > 100) {
                                 fprintf(stderr,
                                         "Invalid min number of moves"
-                                        "(0 <= m <= 100).\n");
+                                        "(0 <= N <= 100).\n");
                                 return a;
                         }
                         a->opts->min_moves = val;
@@ -172,7 +172,7 @@ solve_parse_args(int c, char **v)
                         if (val < 0 || val > 100) {
                                 fprintf(stderr,
                                         "Invalid max number of moves"
-                                        "(0 <= M <= 100).\n");
+                                        "(0 <= N <= 100).\n");
                                 return a;
                         }
                         a->opts->max_moves = val;
@@ -196,7 +196,18 @@ solve_parse_args(int c, char **v)
                         a->opts->max_solutions = val;
                         fixedmsols = true;
                 } else if (!strcmp(v[i], "-o")) {
-                        a->opts->optimal_only = true;
+                        a->opts->optimal = 0;
+                        infinitesols = true;
+                } else if (!strcmp(v[i], "-O") && i+1 < c) {
+                        val = strtol(v[++i], NULL, 10);
+                        if (val < 0 || val > 100 ||
+                            (val == 0 && strcmp("0", v[i]))) {
+                                fprintf(stderr,
+                                        "Invalid max number of moves"
+                                        " (0 <= N <= 100).\n");
+                                return a;
+                        }
+                        a->opts->optimal = val;
                         infinitesols = true;
                 } else if (!strcmp(v[i], "-N")) {
                         a->opts->can_niss = true;
@@ -447,7 +458,8 @@ read_scramble(int c, char **v, CommandArgs *args)
         for(i = 0; i < c; i++) {
                 aux = new_alg(v[i]);
                 if (aux->len == 0) {
-                        fprintf(stderr, "Error: %s unrecognized\n", v[i]);
+                        fprintf(stderr, "Error: %s or its argument"
+                            "unrecognized\n", v[i]);
                         free(aux);
                         return false;
                 }
diff --git a/src/cubetypes.h b/src/cubetypes.h
index 6d8af21..1b679aa 100644
--- a/src/cubetypes.h
+++ b/src/cubetypes.h
@@ -279,7 +279,7 @@ solveoptions
         int                       max_moves;
         int                       max_solutions;
         int                       nthreads;
-        bool                      optimal_only;
+        int                       optimal;
         bool                      can_niss;
         bool                      verbose;
         bool                      all;
diff --git a/src/solve.c b/src/solve.c
index 931dc02..79e421d 100644
--- a/src/solve.c
+++ b/src/solve.c
@@ -373,7 +373,7 @@ niss_makes_sense(DfsArg *arg)
 AlgList *
 solve(Cube cube, Step *step, SolveOptions *opts)
 {
-        int d;
+        int d, op;
         AlgList *sols;
         Cube c;
 
@@ -396,16 +396,19 @@ solve(Cube cube, Step *step, SolveOptions *opts)
                 return sols;
         }
 
+        op = -1;
         for (d = opts->min_moves;
              d <= opts->max_moves &&
-                 !(sols->len && opts->optimal_only) &&
-                 sols->len < opts->max_solutions;
+               !(opts->optimal != -1 && op != -1 && opts->optimal + op < d) &&
+               sols->len < opts->max_solutions;
              d++) {
                 if (opts->verbose)
                         fprintf(stderr,
                                 "Found %d solutions, searching depth %d...\n",
                                 sols->len, d);
                 multidfs(c, step, opts, sols, d);
+                if (sols->len > 0 && op == -1)
+                        op = d;
         }
 
         return sols;