Compilare: user.cpp: In function ‘int solve(int, int)’: user.cpp:38:27: warning: array subscript has type ‘char’ [-Wchar-subscripts] return ret=a[s[st]][s[dr]]; ^ user.cpp:38:34: warning: array subscript has type ‘char’ [-Wchar-subscripts] return ret=a[s[st]][s[dr]]; ^ user.cpp:45:63: warning: array subscript has type ‘char’ [-Wchar-subscripts] ret=min(ret, solve(st+1,i-1)+solve(i+1,dr)+a[s[st]][s[i]]); ^ user.cpp:45:69: warning: array subscript has type ‘char’ [-Wchar-subscripts] ret=min(ret, solve(st+1,i-1)+solve(i+1,dr)+a[s[st]][s[i]]); ^ user.cpp: In function ‘int main()’: user.cpp:53:14: warning: suggest parentheses around ‘+’ inside ‘>>’ [-Wparentheses] cin>>n>>s+1; ^