View Compilation Error

0_0_13649486_1619.cpp: In function 'int cal(char*, char*, int, int)':
0_0_13649486_1619.cpp:20:23: error: 'res' was not declared in this scope
             if(j==lt) res=min(res,dp[i][j]);
                       ^
0_0_13649486_1619.cpp:22:12: error: 'res' was not declared in this scope
     return res;
            ^