View Compilation Error

0_0_18442672_28898.c: In function 'dfs':
0_0_18442672_28898.c:13:5: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
     for(int i = 0 ; i <= end ; ++ i){
     ^
0_0_18442672_28898.c:13:5: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_18442672_28898.c: In function 'dfs1':
0_0_18442672_28898.c:44:5: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
     for(int i = 0 ; i <= end1 ; ++ i)
     ^
0_0_18442672_28898.c:45:9: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
         for(int j = 0 ; j <= end2 ; ++ j){
         ^
0_0_18442672_28898.c: In function 'solve1':
0_0_18442672_28898.c:61:5: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
     for(int i = 0 ; i < top ; ++ i){
     ^